Apparatus for making plastic-embedded specimens

ABSTRACT

A method and an apparatus for embedding entomological specimens or the like in a clear transparent plastic material, wherein the method comprises positioning the specimen between layers of thermoplastic resin material in granular or powder form and confining the same in a suitable die cavity, with provision for preheating the die cavity, applying heat sufficient to melt the resin without appreciable pressure, placing the melted material under predetermined pressure and heating to a temperature sufficient for polymerization, vacuumizing to remove excess gases, cooling the liquified material to set the same and removing the resultant solid plate from the cavity. The apparatus comprises a female molding member in the form of a rectangular frame adapted to be positioned on a Pyrex glass plate, with electrical means for heating the same, means for circulating a cooling liquid through the walls of the frame, and means for vacuumizing the cavity, and a cooperating male molding member which comprises a punch with heating means and a conduit therein for circulating a cooling fluid which molding member is arranged on a piston for operation by an air cylinder mounted above the female molding member so as to telescope the punch within the die cavity. Provision is made for replacing the mold forming members with other members of different size.

United States Patent Donald C. Nicholson 811 11th St., Rock island. Ill.61201 [72] Inventor [21 Appl No 850,476 [22] Filed Aug. 15,1969 I 45]Patented Aug. 3, 1971 [54] APPARATUS FOR MAKING PLASTIC-EMBEDDED PrimaryExaminer-J. Howard Flint, Jr. Anorne \--Greist. Lockwood. Greenawalt &Dewey ABSTRACT: A method and an apparatus for embedding entomologicalspecimens or the like in a clear transparent plastic material, whereinthe method comprises positioning the specimen between layers ofthermoplastic resin material in granular or powder form and confiningthe same in a suitable die cavity, with provision for preheating the diecavity, applying heat sufficient to melt the resin without appreciablepressure, placing the melted material under predetermined pressure andheating to a temperature sufficient for polymerization, vacuumizing toremove excess gases, cooling the liquified material to set the same andremoving the resultant solid plate from the cavity. The apparatuscomprises a female molding member in the form of a rectangular frameadapted to be positioned on a Pyrex glass plate, with electrical meansfor heating the same, means for circulating a cooling liquid through thewalls of the frame, and means for vacuumizing the cavity, and acooperating male molding member which comprises a punch with heatingmeans and a conduit therein for circulating a cooling fluid whichmolding member is arranged on a piston for operation by an air cylindermounted above the female molding member so as to telescope the punchwithin the die cavity. Provision is made for replacing the mold formingmembers with other members of different size.

PATENIED M18 3m: 3,596.31?

sum 1 0F 2 INVENTOR DONALD C. NICHOLSON /KZMWAM ATT' Y5.

PATENTEDAUI; 3m

SHEET 2 OF 2 INVENTOR ICHO ATT'YS.

NALD C. W

APPARATUS FOR MAKING PLASTIC-EMBEDDED SPECIMENS This invention relatesto fabrication of plates of transparent plastic material having embeddedtherein entomological specimens or the like and is more particularlyconcerned with an apparatus for arranging the specimens between layersof meltable plastic material and thereafter controlling the temperatureand applying sufficient pressure so as to enable the plastic to bepolymerized and set.

Numerous procedures have been suggested for embedding specimens ofvarious kinds in plastic materials so as to preserve the same or fordecorative or other purposes. Many of these procedures have involvedcoating or otherwise immersing the specimens in a plastic material whichis in a liquid state and thereafter treating the plastic to harden thesame. In some procedures a mold has been employed to confine thematerial and determine the final shape of the product. However, none ofthe procedures and apparatus heretofore provided have been found fullysatisfactory for embedding in plates or blocks of plastic materialarticles which are relatively fragile and easily damaged by handling andwhich may be destroyed when placed in a high-pressure andhigh-temperature environment. It is an object therefore of the presentinvention to provide an improved apparatus for embedding in plates orblocks of thermoplastic resin articles, such as, entomological orlepidoptera specimens, so as to preserve the specimens in an undamagedcondition.

A more specific object of the invention is to provide an apparatus forembedding entomological specimens, or the like, in a clear plasticmaterial which comprises means for positioning the specimens betweenlayers of a meltable plastic material in granular form while confiningthe same in a cavity in a female molding member, thereafter closing thecavity without appreciable pressure on the plastic and specimenassembly, heating the cavity to a sufficient degree to melt the plastic,applying sufticient heat and pressure to the melted plastic topolymerize the plastic, vacuumizing the cavity, and cooling the same soas to set the plastic and form a transparent plate with the specimenembedded therein.

Another object of the invention is to provide a molding apparatus forembedding entomological specimens, or the like, in plastic materialwhich comprises a female molding member having a cavity within whichlayers of plastic material in granular form may be arranged with adesired specimen interposed between the layers of material which supportthe specimen in the desired position and a cooperating male moldingmember or punch which is mounted on the end of a fluidactuated plungerwith the latter positioned so that the punch will telescope within thecavity, and means for heating and cooling the molding members so as tofirst heat the cavity to a temperature sufficient to melt the plasticand thereafter to polymerize the plastic and finally to cool the productwhile under a predetermined pressure applied through the male moldingmember.

A further object of the invention is to provide a molding pressparticularly designed for embedding specimens of a relatively fragilenature in a thermoplastic resin which comprises a bottom female moldingframe adapted to be seated on a highly polished surface and having acavity of a size and shape desired for the finished product with heatingand cooling means operable to control the temperature in the cavity, anda cooperating top male molding member in the form of a punch mounted forreciprocating movement on a fluid-operated piston which enables thepunch to be telescoped into the cavity in the bottom molding frame, themale molding member also having temperature controlling heating andcooling means, and means for connecting a vacuum line to the bottommolding frame for withdrawing air and gases from an assembly of granularresin and a specimen or specimens buried between layers of the resinwhich is disposed in the cavity so that the resin may be liquified,polymerized, and set, to form a plate with the specimen or specimensembedded therein.

These and other objects and advantages of the invention will be apparentfrom a consideration of the apparatus which is shown by way ofillustrations in the accompanying drawings wherein:

FIG. I is a perspective view of a plastic plate having an en tomologicalspecimen embedded therein which has been produced by employing theapparatus of the invention;

FIG. 2 is a side elevation of an apparatus embodying the invention, theapparatus being shown with the top and bottom molding members inseparated position;

FIG. 3 is a vertical section taken on a plane at right angles to theplane of FIG. 2 with the molding members in cavity closing, operativeposition, the view being taken on the line 3-3 of FIG. 4;

FIG. 4 is a plan view, taken on the line 4-4 of FIG. 2, showing thebottom molding member in position for receiving the plastic and thespecimen or specimens to be embedded therein; and

FIG. 5 is a horizontal cross section taken on the line 5-5 of FIG. 2.

Referring first to FIG. 1 of the drawings there is illustrated a moldedplastic plate 10 in which there has been embedded an entomologicalspecimen 12 which in the illustration is a butterfly. The plate 10 is ofgenerally rectangular form and is transparent so that the specimen isclearly visible and all exposed areas may be observed through theplastic material. A suitable molding material is a synthetic resin whichis meltable and in the finished product is optically transparent. It maybe, for example, an acrylic resin, such as, a polymethyl-methacrylate,or other transparent synthetic plastic. Commercial products sold underthe names Lucite, Plexiglass and Perspex are suitable and are readilyavailable in crystallin or powder form.

An apparatus suitable for practicing the invention is illustrated inFIGS. 2-5. The apparatus comprises a bottom mold assembly 14 and a topmold assembly 16 which cooperates with the bottom assembly 14 in forminga molding cavity in which the resin and the desired specimen orspecimens are enclosed during the processing required for polymerizingand setting the resin to form the finished plate.

The lower molding assembly 14 comprises a bed or baseforming member 18(FIG. 2) covered with a heat-insulating pad or sheet of asbestos, or thelike, as indicated at 20 on which there is positioned an aluminum blockor plate member 22 (FIGS, 2 to 5) having mounted in suitable recessestherein three heating elements 24, each having provision for connectionto an electrical supply line. The block 22 also has a conduit 26 builtinto the same with connections, indicated at 28, for attaching a fluidline so as to circulate water or other liquid. The block 22 is adaptedto support on its upper face a relatively thin stainless steel plate 30on the top of which a Pyrex glass plate 32 is adapted to be positioned,the latter forming the bottom or floor of a molding cavity 34 which isdefined by a rectangular steel frame 36 having a chrome plated surface.The molding frame 36 constitutes a female molding die with a cavity 34dimensioned according to the size desired for the plate which is to beformed. The die frame 36 is adapted to be held in position on the frame22 by means of a pair of oppositely disposed clamps 38. Each of theclamps 38 consists of a base plate 40 which has a depending bracket 42bolted or otherwise secured to the frame 22. There is a topclampingplate 44 pivoted on a spacer 45 above the plate 40 and connected to thebottom plate 40 by one or more bolts 46, with a compression spring 48carried thereon and holding the top plate 44 elevated so that the frame36 and glass 32 can be slid into position from the side of the assemblywhich is free of the clamps. The die frame 36 is provided in itsvertically positioned walls with a liquid receiving conduit 50 havingsuitable means, as indicated at 51, for connecting to a fluid supply topermit circulation of liquid therein. The liquid conduit 50 may beconveniently formed by boring the sidewalls and plugging the ends of thebores, except for connections 51, where required to form a continuousconduit as shown in FIG. 4. Electric heating elements are also disposedin suitable recesses in the frame walls as indicated at 52. At apredetermined level there is a groove extending about the perimeter ofthe cavity, as indicated at 53, which is provided with a series ofoutlets and a connection, as at 54, with a vacuum line, so that thecavity 34 may be evacuated after it is closed by descent of thetelescoping punchlike upper die member 56 which depends from the topmold assembly 16.

The upper molding assembly 16 comprises the punchlike die member 56which depends from an aluminum block 58 forming a base therefor. Theblock 58 corresponds to the block 22 in the bottom mold assembly 14 andis provided with heating elements and a fluid-circulating conduit in thesame manner as the block 22 and as shown in FIG. 5. The block 58 isprovided with a pair of oppositely disposed angular clamp members 60,each with a clamping bolt 62, so as to provide for detachable support ofthe punch 56 and block 58 on a steel support plate or block 64. Theblock 58 carries three heating elements indicated at 66 with suitableattachments for connection with an electrical supply line and also has afluid conduit, indicated at 67 with connections for a waterline in thesame manner as block member 22. The block 64 is bolted or otherwiseattached to the bottom plate 68 which is mounted on the end of thepiston 70, the latter depending from an air cylinder 72 which issuitably supported on a stand or other mounting frame (not shown). Thesupport block 64 has heaters 73 mounted in suitable recesses withconnections for attachment to a suitable current supply line. Anasbestos insulating pad 74 may be interposed between the base block 64and piston head 68. The die member 56 is provided with heating elements76 and a fluid conduit 78 which may be arranged in the same manner as inFIG. but in vertically offset planes as indicated in FIG. 2. Thepunchlike die member 56 and its associated base block 58 and clampmember 60 form a detachable unit so that the apparatus maybe adapted forforming plates of different dimensions by substitution of the right sizepunch and die members.

While the lower die frame 36 is shown with a single cavity 34, multiplecavities may be provided by inserting suitable dividers of the properheight. 7 I

in using the apparatus, the proper size punch and die members areselected and positioned in the press after which the upper assembly 16is lowered'a sufficient distance to permit the bottom die frame 36 to beproperly aligned for telescoping movement of the punch member 56 intothe cavity 34, the spring clamps 38 permitting limited lateraladjustment of the frame 36. The punch member 56 is then lowered apredetermined distance into the cavity 34, after the mold surfaces havebeen sprayed or otherwise treated with silicon or other lubricant tofacilitate release of the product when it is completed. In a typicalforming operation, the mold cavity 34 is initially preheated, after themold surfaces including the Pyrex plate 32, have been sprayed with arelease agent or lubricant. The Pyrex glass plate 32 is cleaned and slidinto place first with the female mold frame 36 positioned on the topthereof and centered relative to the punch 56 for clamping intoposition. The heating elements are then activated to preheat the cavity34 to approximately 150 F the heating being controlled by suitablethermostatic controls (not shown). The mold cavity 34 is then opened bywithdrawing the punch 56 and a layer of granular or powdered resinmaterial, for example, methylmethacrylate, is spread evenly over thebottom portion of the cavity 34. The specimen 12 is then placed on thetop of the layer of resin material, the latter supporting the specimen12 in the position desired. Another layer of the resin material is thenspread over the specimen making sure that the vacuum ports in the recessor groove 53 are not obstructed. The punch member 56 is then lowered toa position where it is supported on a pair of heat-resistant shocks 80(F K]. 3) of rubber or like material, which are in the form ofrectangular blocks. The shocks 80 are positioned on the peripheralmargins of the frame 36 which are free of the clamps 38 so as to limitthe entry of the punch member 56 into the mold cavity 34. This preventscrushing of the specimen by the weight of the punch member 56 bearing onthe resin. The heating elements are then activated to build up the heatto approximately 210 F. which liquifies the resin and the rubber shocksare removed, allowing the punch 56 to float and descend by gravity whilethe temperature is raised to approximately 275 F. to allow for finalpolymerization of the resin. At this temperature, the heat is shut offand vacuum is applied in order to allow time for complete melting of theplastic material and permitting final vacuum eradication of excess heatand gases. The temperature is allowed to drop down to approximately 250F. when the mold and punch cooling systems are activated to cool downthe cavity and the melted resin with the vacuum still on and the punch56 sliding down by gravity only. A relatively low pressure between 0.1and 1.5 pounds per square inch is applied through the cylinder 72 to thepunch 56 and held until the resin is set so as to maintain a standardlevel and halt any resurgence of heat from top and bottom elements whichmight otherwise result in ballooning or swelling of the surfaces. Thecooling system is activated to circulate water to cool the mold andcavity 34 at approximately 200 F. switching from hot to cold water, withthe water being recirculated throughout the system. At approximately F.,the cooling system is disconnected and pressure released on the punch 56so that the latter may be withdrawn from the mold cavity 34 after whichthe frame 36 may be slid out from beneath the clamps 38 to release thefinished product, the vacuum having been disconnected.

While specific temperatures are referred to in the example described, itwill be understood that the exact temperature or range of temperature ineach instance will depend upon the specific product which is employed asthe resin material.

I claim:

1. Apparatus for use in embedding specimens in plastic resin material,which material is initially in granular form and is adapted to meltunder heat and which polymerizes and sets into solid form underpredetermined heat and pressure, said apparatus comprising a lowerfemale mold member in the form of a frame which defines a cavity ofgreater depth than the thickness desired for the finished product, asupport for said female mold frame, said female mold frame havingheating means and means forming a conduit through which liquid ofpredetermined temperature may be circulated to control the temperatureof said cavity, said female mold frame having a vacuum connection withopenings into said cavity at a predetermined depth to permit withdrawalof air and gases from said cavity when the latter is closed, and anupper male mold member mounted on a reciprocable support above thefemale mold member and constructed so that it may be moved to telescope,at least in part, into the cavity in said female mold frame and closesaid cavity, said male mold member having heating means and meansforming a conduit through which liquid of predetermined temperature maybe circulated to control the temperature of said support for said femalemold frame having oppositely disposed members adapted to adjustablyclamp said female mold frame thereon, said male mold member.

2. Apparatus as set forth in claim 1, and a plate member having apolished surface adapted to be positioned on said support for saidfemale mold frame so as to form a bottom for said cavity.

3. Apparatus as set forth in claim 1, and said oppositely disposed clampmembers forming guide channels for receiving in sliding relation thereinand initially positioning said female mold frame and associated members.

4. Apparatus as set forth in claim 1, and said support for said femalemold frame having heating elements and a conduit adapted to receivecirculating liquid of predetermined temperature.

5. Apparatus as set forth in claim 1, and said male mold member beingmounted on a baseplate which base plate has heating means and meansforming a conduit for circulating fluid of a predetermined temperature.

necting said baseplate to said support block.

8. Apparatus as set forth in claim 7, and said base plate and supportblock having heating means and means forming a conduit in said baseplate with means for connecting to a fluid supply line.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 'g5c;6.'g17 Dated August 3, 1971 Inventor(s) Donald C Nicholson It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 4, line #0, after "frame," (first occurrence) insert --saidsupport for said female mold frame having oppositely disposed membersadapted to adjustably clamp said female mold frame thereon,-

Column 4, lines 53, 5 and 55, delete "said support for said female moldframe having oppositely disposed members adapted to adjustably clampsaid female mold frame thereon,"

Signed and sealed this 15th day of August 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Atte sting Officer Commissionerof Patents W. mm 1...? a ..v.-.- v i ORM pomso (069] uscoMM-oc 60376-PB9

1. Apparatus for use in embedding specimens in plastic resin material,which material is initially in granular form and is adapted to meltunder heat and which polymerizes and sets into solid form underpredetermined heat and pressure, said apparatus comprising a lowerfemale mold member in the form of a frame which defines a cavity ofgreater depth than the thickness desired for the finished product, asupport for said female mold frame, said female mold frame havingheating means and means forming a conduit through which liquid ofpredetermined temperature may be circulated to control the temperatureof said cavity, said female mold frame having a vacuum connection withopenings into said cavity at a predetermined depth to permit withdrawalof air and gases from said cavity when the latter is closed, and anupper male mold member mounted on a reciprocable support above thefemale mold member and constructed so that it may be moved to telescope,at least in part, into the cavity in said female mold frame and closesaid cavity, said male mold member having heating means and meansforming a conduit through which liquid of predetermined temperature maybe circulated to control the temperature of said support for said femalemold frame having oppositely disposed members adapted to adjustablyclamp said female mold frame thereon, said male mold member. 2.Apparatus as set forth in claim 1, and a plate member having a polishedsurface adapted to be positioned on said support for said female moldframe so as to form a bottom for said cavity.
 3. Apparatus as set forthin claim 1, and said oppositely disposed clamp members forming guidechannels for receiving in sliding relation therein and initiallypositioning said female mold frame and associated members.
 4. Apparatusas set forth in claim 1, and said support for said female mold framehaving heating elements and a conduit adapted to receive circulatingliquid of predetermined temperature.
 5. Apparatus as set forth in claim1, and said male mold member being mounted on a baseplate which baseplate has heating means and means forming a conduit for circulatingfluid of a predetermined temperature.
 6. Apparatus as set forth in claim1, and the support for said male mold member comprising a fluid cylinderhaving a piston with means thereon for connecting the male mold member.7. Apparatus as set forth in claim 1, and the support for said male moldmember comprising a fluid cylinder having a piston and a support blockon said piston, and said male mold member having a baseplate and meansfor detachably connecting said baseplate to said support block. 8.Apparatus as set forth in claim 7, and said base plate and support blockhaving heating means and means forming a conduit in said base plate withmeans for connecting to a fluid supply line.